*: use default 1s for schema lease.

interpreter/main.go

@@ -35,7 +35,7 @@ var (
 	logLevel = flag.String("L", "error", "log level")
 	store    = flag.String("store", "goleveldb", "the name for the registered storage, e.g. memory, goleveldb, boltdb")
 	dbPath   = flag.String("dbpath", "test/test", "db path")
-	lease    = flag.Int("lease", 300, "schema lease seconds, very dangerous to change only if you know what you do")
+	lease    = flag.Int("lease", 1, "schema lease seconds, very dangerous to change only if you know what you do")
 
 	line        *liner.State
 	historyPath = "/tmp/tidb_interpreter"

tidb-server/main.go

@@ -34,7 +34,7 @@ var (
 	storePath = flag.String("path", "/tmp/tidb", "tidb storage path")
 	logLevel  = flag.String("L", "debug", "log level: info, debug, warn, error, fatal")
 	port      = flag.String("P", "4000", "mp server port")
-	lease     = flag.Int("lease", 300, "schema lease seconds, very dangerous to change only if you know what you do")
+	lease     = flag.Int("lease", 1, "schema lease seconds, very dangerous to change only if you know what you do")
 )
 
 func main() {

tidb.go

@@ -92,12 +92,13 @@ var (
 	// store.UUID()-> IfBootstrapped
 	storeBootstrapped = make(map[string]bool)
 
-	// SchemaLease is the time(seconds) for re-updating remote schema.
+	// schemaLease is the time for re-updating remote schema.
 	// In online DDL, we must wait 2 * SchemaLease time to guarantee
 	// all servers get the neweset schema.
-	// Default schema lease time is 300 seconds, you can change it with a proper time,
+	// Default schema lease time is 1 second, you can change it with a proper time,
 	// but you must know that too little may cause badly performance degradation.
-	schemaLease = 300 * time.Second
+	// For production, you should set a big schema lease, like 300s+.
+	schemaLease = 1 * time.Second
 )
 
 // SetSchemaLease changes the default schema lease time for DDL.